This Data Brief (PDF version available here) presents an analysis of excess mortality (increase in deaths) for California in 2020, using California vital statistics death data (death certificates), and includes assessment of differential increases by race/ethnic group, age, and increases in deaths due to conditions other than COVID-19. This analysis is a follow-up to findings in the 2020 State of Public Health Report, part of the State Health Assessment.
These data show that after many years of decreasing death rates in California, the rate increased substantially (15.9%) in 2020, and continued to increase in 2021. This increase in deaths, or “excess mortality”, is due to COVID-19 and to other causes of death.
Excess mortality differed by race/ethnicity, with striking increases among Latinos. Compared to prior years, deaths increased 34.1% among Latinos, about 20% among other groups, and 7.8% among Whites. As the year proceeded, excess mortality increased within all racial groups, and disparities between groups increased. Among Latinos, there was a 65.0% increase in the 4th quarter.
Increases in deaths from conditions other than COVID-19 were observed, including deaths from drug overdoses (47.2%), homicide (32.8%), Alzheimer’s disease and other dementias (10.0%), and ischemic heart disease (4.6%). These 2020 increases in homicide and ischemic heart disease death rates are in contrast to many prior years of decreasing or level rates.
The increase in death rate differed by age deferentially among race/ethnic groups. Of particular note, the overall death rate increased sharply among young blacks (aged 5-14 and 15-24) and American Indian/Alaska Natives aged 35-44. In general, a large proportion of the increase in deaths among older persons was due to COVID-19 while a large proportion of the increase in deaths among younger persons was due to other conditions.
As the pandemic intensified throughout 2020, the increases in the rates accelerated. Comparing the 1st quarter of 2020 to the 1st quarter of 2019, death rates were similar, with just a 0.4% increase; then, comparing 2nd quarters, there was a 10.2% increase; comparing 3rd quarters, a 23.1% increase; and when comparing 4th quarters, a 30.8% increase.
The rate in the 1st quarter of 2021 (Q1-2021) was higher than all quarterly rates in 2020, and much higher than any other recent prior quarter.
Deaths among all race/ethnic groups were higher in quarters 2, 3, and 4 of 2020 compared to the average rate of the corresponding 2017-2019 quarters. As the year progressed, these differences within each race/ethnic group increased for all race/ethnic groups, and disparities in rates between groups increased.
These disparities are seen in Figure 3a by observing the increasing gap within any specific race/ethnicity group (dotted line compared to solid line), and by observing the increasingly larger gaps in some groups than others.
These increases are all statistically significant for all groups. (See Appendix Figure Set 1)
Rates continued to increase substantially for all race/ethnic groups in Q1-2021. In Q1-2021, the Latino rate surpassed the AI/AN rate.
Aside from COVID-19, three conditions with large percent increases in deaths from 2019 to 2020 were drug overdose (47.2%), homicide (32.8%), and diabetes (17.7%), Table 2.
The conditions with the largest absolute increases in number of deaths from 2019 to 2020 were Alzheimer’s disease and other dementias (3,623), ischemic heart disease (2,778), and drug overdoses (2,748).
For drug overdose deaths, the increases are consistent with recent trends, albeit accelerated. For Alzheimer’s disease and other dementias, the increases are consistent with long-term increasing trends, but a sharp reversal of decreasing trends the past two years. But for ischemic heart disease, the leading cause of death in California, the apparent increase is a concerning reversal of a steady downward trend of many prior years. The increase in homicide is also striking and alarming, in contrast to the encouraging decreases the last few years, and the long-term downward trend. (For long-term trends in cause-specific deaths in California, see Appendix Figure Set 2 or the California Community Burden of Disease Engine (CCB).)
Regarding decreases from 2019 to 2020, suicide/self-harm and lung cancers both had noteworthy decreases.
Figure 4 below shows 2017-2020 quarterly trends in conditions that had large percentage or large absolute increases from 2019 to 2020 (detailed data in Appendix Table 1).
As noted above, homicide deaths increased substantially in 2020, and strikingly by quarter. Homicide rates increased 23% in the 2nd quarter, 45% in the 3rd quarter and 58% in the 4th quarter 2020 compared to respective quarters in 2019.
COVID-19 emerged in early 2020 and deaths increased rapidly not only in California, but almost everywhere, as a massive global pandemic. In the 4th quarter of 2020 and 1st quarter of 2021, COVID-19 was, by far, the leading cause of death in California.
In general, a large proportion of the increase in deaths among older persons was due to COVID-19 while a large proportion of the increase in deaths among younger persons was due to other conditions.
As seen in Figure 5, the greatest percentage increases in the number of deaths were among older Latinos, younger Blacks, and 35-44 year-old AI/AN (detailed data in Appendix Figure Set 3 and Appendix Table 2).
The striking increases among Blacks ages 5-14 and 15-24 are particularly concerning for a range of reasons. It is also important to note that these large percentage increases among young persons represent a smaller total number of deaths than among older persons.
Of the 465 deaths (an increase of 156 deaths) among 15-24 year old Blacks in 2020, the greatest contributing causes were homicide, road injury, and drug overdose. Specifically, 138 (increase of 23 deaths) were due to homicides, 85 (increase of 31) to road injury, 76 (increase of 42) to drug overdoses, and 18 (increase of 8) to “ill-defined” conditions, some of which will be clarified in the coming months. These concerns are of course not restricted to just one race/ethnic group. For example, these same causes were leading contributors to the 1,966 deaths among Latinos aged 15-24 in 2020. Specifically, 467 (increase of 242 deaths) were due to drug overdoses, 333 (increase of 84) to homicide, 418 (increase of 71) to road injury, as well as 61 (increase of 33) to “ill-defined” conditions and to COVID-19. These cause-specific data by race/ethnicity and age are available in Appendix Table 3.
Of the 106 deaths (an increase of 46 deaths) among 35-44 year old AI/AN in 2020, the greatest contributing causes were drug overdose, 22 (increase of 14 deaths) and road injury, 11 (increase of 6).
This Data Brief was developed as a part of the broader State Health Assessment, and builds on the 2020 State of Public Health report.
Death data are from the California Integrated Vital Records (CalIVRS) system, based on death certificates/reports transmitted to the California Department of Public Health, Center for Health Statistics and Informatics (CHSI):
All death numbers and rates in this analysis are based only on the primary underlying cause of death, not on any secondary contributing factors (i.e. no “multiple cause of death” codes are included).
Deaths in this Data Brief are based on this vital statistic data, and death numbers may differ from numbers reported based on other systems. In particular, numbers of deaths from COVID-19 may differ from COVID-19 death numbers posted on CDPH, National, or other web sites. Those sites can include reports of deaths from sources other than death certificates and/or on deaths where COVID-19 is not listed as the “primary” cause of death.
The grouping of ICD-10 cause of death codes into condition categories is based on the California Burden of Disease System, a California-modified version of the Global Burden of Disease system. Details of this system are available on the California Community Burden of Disease Engine (CCB), in the About -> Technical Documentation tab. Of specific note for this Data Brief:
“COVID-19” is based on ICD-10 codes U07.1.
The “Drug overdose” condition includes “accidental poisonings by drugs” codes (X40-X44) and “substance use disorder codes” (F11-F16, F18, F19), but not “alcohol use disorder” (F10). The drug overdose condition also includes “newborn (suspected to be) affected by maternal use of drugs of addiction” (P044).
Population denominator data for rate calculations are from the California Department of Finance (DOF) Population Projections (Baseline 2019) Table P-3: Complete State and County Projections Dataset.
Unless otherwise specified, the term “rate” throughout this Data Brief means age-adjusted death rate per 100,000 population.
Age-adjusted rates are calculated using the “direct” method, with the CDC standard 2000 projected U.S. population published by CDC/NCHS in January 2001–specifically, Table 2, Distribution #1 was used, but with age groups <1 and 1-4 combined.
Excess mortality measures how much higher (or lower) mortality is in one time period or group compared to another. Excess mortality in the context of the COVID-19 pandemic is generally the mortality in a particular COVID-19-impacted time period, like 2020, compared to a prior period not impacted by COVID-19, like 2019. Other periods can be used too, like specific ranges of weeks, months or quarters. Excess mortality in this Brief compares rates in 2020 to ‘baseline’ rates in 2019, or the average of 2017-2019, using full year or quarters .
Race/ethnicity is grouped and coded using standard CDPH methods and is detailed in the CCB technical documentation. Persons coded as “multi-race” are excluded from race-specific data, because numerator-denominator mis-alignment makes such rates uninterpretable.
The data in Table 2 were first restricted to causes of death for which there were > 500 deaths in any year, 2017-2020. Then, among those causes, the data were restricted to causes that had among the top five relative (percent change in age-adjusted death rate) or absolute (change in number of deaths) increases from 2019 to 2020 or among the bottom three relative or absolute decreases.
The data in Figure 4 and Appendix Table 2 are restricted to causes of death for which there were > 500 deaths in any quarter of any year, 2017-2020, and among those the causes that were among the top three relative or absolute increases from Quarter 2, 3 or 4 in 2019 to the same quarter in 2020.
For Figure 5, the overall length of each bar is the percent increase in the number of deaths from all cases from 2019 to 2020 in the specific age and race/ethnic group. The “Cause Index” was constructed by first calculating the ratio of the number of COVID-19 deaths (in 2020) in each group to the total increase in the number of deaths in that group. If that ratio was greater than 1.0 (i.e. the number of COVID-19 deaths in 2020 was greater than the increase in number of deaths from 2019 to 2020), the ratio was set to one. The COVID-19 proportion of each bar is the product of that ratio and that overall percent increase; the “Other cause” proportion is the remainder of each bar.
All analysis and data display were conducted using R and this document was generated using R markdown. All data and numbers in this document were generated/extracted directly from the data; no numbers were “hand transcribed”. This approach provides internal documentation and facilitates updating, reproducibility, and reuse.
All data and visualizations in the Data Brief are available at the county level, at the request of the respective county health department.
An Excel file with data for all charts above can be downloaded here.
Deaths increased 15.8% in 2020 compared to 2019, with most of this increase due to COVID-19. The death rate increased as the year progressed–COVID-19 was the leading cause of death in the 4th quarter of 2020, with a 30.8% increase in the death rate that quarter compared to the 4th quarter of 2019. Deaths among Latinos increased 34.3% in 2020, including a staggering 65.0% increase in the 4th quarter compared to the 4th quarter of 2019.
Deaths from a number of other conditions also increased, including drug overdoses, Alzheimer’s disease and other dementias, homicide, ischemic heart disease, and others. The increase in ischemic heart disease, the leading cause of death in California, is a reversal of a 20 year downward trend. The sharp increase in homicides reverses three prior years of decreases, and results in rates not seen since 2007. Charts showing these trends are available in the Appendix and are available for all California counties.
Overall suicide rates decreased from 2019 to 2020. This observation is being investigated and it is clear that this trend differs by multiple factors including age, race/ethnicity, and place. Sadly, there appears to be a noteworthy increase in suicides among the 5-14 year-old age group (see Appendix Table 3), mostly among Latinos and Blacks. Further analysis of violence impacting specific populations and regions is urgently needed.
As has been well described, older persons are at elevated risk for severe outcomes of COVID-19 infection including death. Among all groups, COVID-19 cases-fatality rates increase sharply with increasing age. However, because of a combination of 1) the differences in age-specific incidence of COVID-19 across race/ethnic groups, 2) the differences in the population age distribution of different race/ethnic groups in California, and 3) differences in case fatality rates, there are substantial differences in the age distributions of COVID-19 deaths by race/ethnicity, as seen in Appendix Figure 4. Of note, the largest proportion of COVID-19 deaths among Whites and Asians is among the 85+ year old age group, whereas the largest proportion of COVID-19 deaths among Latinos, Blacks, NH/PI, and AI/AN is among the 65-74 year-old age group. And, the latter four groups have substantial numbers of COVID-19 deaths among persons less than 55 years of age, whereas Whites and Asians do not.
These data do not provide insight into what role COVID-19 has had in these observed increases, or on decreases in other conditions. It is logical to think that COVID-19 caused changes and delays in access to care, changes in social support, and changes in eating, drinking, exercising and other behaviors, all of which could have had important impacts on health.
The increase in deaths among young persons, particularly the 63.9% increase among 5-14 year-old Blacks and the 50.5% increase among 15-24 year-old Blacks is highly concerning. While the underlying absolute numbers are small, the increases are nevertheless concerning on their own, and for their implications of differential health status, social pressures and access to care during the pandemic crisis. Additional investigation of these data will continue, and updates will be provided as they become available.
There are important limitations to this analysis:
The 2020 death data are not fully complete, and some small changes are likely to occur, but they are unlikely to alter any of these observations of state level trends. For example, the proportion of 2020 deaths in the “Ill-defined” category, while very small (0.9%), is larger than in prior years. Some of these deaths will likely be recoded to defined categories eventually (perhaps accentuating slightly observations noted in this report).
The data in this report focus exclusively on the “underlying” or “primary” cause of death, and do not reflect the “contributory” or “multiple cause of death” causes. For example, the 31,033 COVID-19 deaths shown in Table 2 all have COVID-19 listed as the underlying cause of death, but there are an additional 2,146 deaths in 2020 with some other condition listed as the primary cause of death and COVID-19 as a contributing cause. Of these 2,146 the top five primary causes were: Alzheimer’s disease and other dementias (405), Ischemic heart disease (402), Stroke (159), Hypertensive heart disease (113), and Diabetes mellitus (96). Another important example is that there were 1,594 deaths in 2020 with “alcohol disorders” listed as the underlying cause of death, but many more (4,656) with another condition listed as the underlying cause and alcohol disorders listed as a contributory cause. Additional investigation of both contributory and underlying cause of death data is underway.
This analysis does not include data for 2021, when very large increases in death due to COVID-19 are known to have occurred. Those data are currently being investigated with similar lenses to this report.
Reporting on changes in deaths is the “tip of the iceberg” and changes seen in deaths may not fully reflect changes in morbidity. Investigations into changes in rates of hospitalizations, emergency department visits, reportable diseases, and other measures of morbidity are underway. The relationship of these changes in mortality, and morbidity, to the underlying social determinants of health, such as poverty, education, racism, language, and a host of others, are also underway. This ongoing comprehensive assessment and analysis across multiple programs is critical to long-term prevention and equitable improvements in population health.
While this rapid analysis of these readily available vital statistics death data provides clear evidence of important trends, deeper insights and understanding are urgently required. It may be possible to gain insights from additional rapid analysis of other available data including surveillance data, administrative data sets, and other sources. Other critical insights will require longer-term complex research and study designs.
In the information above, excess mortality is calculated as the percent increase in a rate from 2019 to 2020. Other methods can be used, including a method that calculates excess mortality as the increase in the number of death divided by the population size – this method has been used in a published letter assessing excess mortality in California.
Part A in the chart below replicates Figure 2 above, and indicates that Latinos have the highest excess mortality based on percent increase. Part B below uses the other method and indicates that Blacks have the highest excess mortality based on the “excess mortality rate”; and indicates that both American Indian/Alaska Natives and Native Hawaiian/Pacific Islanders have a higher excess mortality rate than Latinos.
The “conclusions” from the two methods differ because of the different ways the methods take into account the rate in the baseline period and the population size. Both of these methods are reasonable and provide different insights.
NOTES:
Social Determinants of Health
Figure 7 - Increase in Death Rate by Race/Ethnicity, and Social Determinants of Health in 2020